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Naturally regenerated 20-25-year-old Scots pine (Pinus sylvestris L.) trees were grown in open-top chambers in the presence of an elevated temperature or CO(2) concentration, or both. The elevated temperature treatment was administered year-round for 3 years. The CO(2) treatment was applied between April 15 and September 15 for 2 years. The photosynthetic responses of 1- and 2-year-old needles to varying photon flux densities (0-1500 micro mol m(-2) s(-1)) and CO(2) concentrations (350, 700 and 1400 micro mol mol(-1)) during measurement were determined. The CO(2) treatment alone increased maximum photosynthetic rate and light-use efficiency, but decreased dark respiration rate, light compensation and light saturation regardless of needle age. In contrast, the temperature treatment decreased maximum photosynthetic rate and photosynthetic efficiency, but increased dark respiration rate, light compensation and light saturation. The aging of needles affected the photosynthetic performance of the shoots; values of all parameters except photosynthetic efficiency were less in 2- than in 1-year-old needles. The CO(2) treatment decreased and the temperature treatment enhanced the reduction in maximum photosynthesis due to needle aging.

The results indicated that dinotefuran is the most effective insecticide for use against imidacloprid-resistant A. gossypii. To avoid further resistance development, the use of nitenpyram, acetamiprid and thiacloprid should be avoided on imidacloprid-resistant populations of A. gossypii.

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Stem respiration is an important component in the annual carbon balance of a Scots pine stand, contributing 9 % to total carbon loss from the ecosystem and consuming about 8 % of the carbon of the ecosystem gross primary production. Stem (or air) temperature was the most important predictor of stem carbon flux. The magnitude of stem respiration is modified by photosynthesis and tree growth. Solar radiation indirectly affects stem respiration through its effect on photosynthesis.

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